In order to make the loader engine and the external load form a good matching state,a kind of walking hydraulic system with variable displacement was designed.On the basis of analyzing the dynamic characteristics of the walking system,the simulation analysis and experimental were carried out.The results show that on the whole,the simulation results can well reflect the operating conditions of straight line driving,and the simulation results and experimental results are in good agreement;during the unilateral turnning test on the loader,there is leakage in the inner wheel motor;after entering the rolling stage,the inner wheel variable pump is driven by the motor,forming a high pressure oil and part of the flow,the plunger pump enters into the pump-motor operation condition,and a certain degree of parasitic power is produced;when entering the uniform bilateral steering stage,the inner and outer wheels resistances are different,which needs to be properly adjusted,so the function of various working conditions can be met to achieve a good running state;when entering the unilateral steering stage,the inner wheels begins to be braking,and the oil in the inner wheel variable pump appears high pressure and forms partial flow.